Several brain malfunctions or diseases are caused or exacerbated by high levels of beta amyloid protein. Examples of these brain malfunctions include Alzheimer's disease, Down Syndrome and Fragile X Syndrome. Alzheimer's disease (AD) is the most common cause of age-related dementia, affecting over 5 million individuals in the US alone. Death as a result of AD occurs, on average, nine years after diagnosis with a devastating effect on quality of life and burden on caregivers throughout the course of the disease.
The first brain structures damaged in AD are those serving short term memory (hippocampus and neighboring temporal lobe). The disease then spreads to the parts of the temporal, parietal and frontal lobes which function in memory, judgment and cognition. Parts of the brain that are specialized for sensory and motor functions are relatively spared, especially the occipital lobe (visual system). The regions of the brain which have been characterized as most vulnerable to AD are known as the “default mode network” (DMN), a system in the cerebral cortex that becomes active when attention isn't focused on a specific mental task. One estimate is that people spend 50% of waking time in the mental activities mediated by the DMN. The DMN is integral in recalling past events, anticipating future events, providing the sense of self and the intuitive grasp of the emotions of others, and making future plans. The DMN has the highest metabolic rate of cortical areas, which likely accounts for its vulnerability in AD. Compounding the problem is that the DMN is spread widely over the cerebral hemispheres, requiring neurons with long axons to maintain coordination. AD causes the DMN to become even more active, possibly in an attempt to compensate for lost neurons.
Conventional therapies for treating AD focus on controlling symptoms rather than halting or slowing progression of the disease. In practice, the benefits of presently-available treatment strategies last typically only up to about 2 years. Drugs which are being tested for treatment of AD may not be available for years. In the meantime, the demand for a course of therapy that halts or slows progression of the disease is enormous.
The currently accepted theory regarding the cause of AD is that the disease results from an excess buildup of a normal protein known as beta amyloid in the brain. Beta amyloid is normally discharged into synapses between neurons and transiently binds to neurotransmitter receptors at nerve cell membranes, after which it is cleared from the synapse by one of several mechanisms, primarily by transport away from the brain through the bloodstream.
There is ample evidence that excess beta amyloid results from diminished clearance of the protein from the brain even when normal protein production levels prevail. The capacity and effectiveness of clearance declines with age; therefore, AD can be viewed as an exaggeration of the effects of normal aging. Most of the insufficiently-cleared beta amyloid protein aggregates outside of cells in structures known as plaques that are visible under a light microscope. At the stage of AD when the loss of neurons begins, the plaques are close to maximal size. Chemical analysis shows up to 1000 times the normal level of beta amyloid in brain tissue from AD patients, and this beta amyloid exists almost entirely in the form of plaque. The toxic form of beta amyloid is one of the small aggregates (dimers, oligomers and fibrils) which reach toxic levels only at a critical concentration. A small decrease in the production of beta amyloid in brain tissue may potentially slow or halt the course of the disease.
Accordingly, methods for treating brain malfunctions which are caused or exacerbated by excessive levels of beta amyloid protein by reducing the production of the beta amyloid in brain tissue through entrainment, binaural beats and/or neurofeedback may be effective in the treatment of AD and other related conditions.